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<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
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<body>
     <script>
            var soc =  prompt("输入成绩")
            soc >= 80 ? alert('优秀')  : alert('渣渣')
     </script>
</body>
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